The purpose of this research study is to find out more about potential drug interactions with the medications losartan and phenytoin. Losartan has been approved by the FDA and is used to treat high blood pressure. Phenytoin has also been approved by the FDA and is most commonly used drug in the treatment of seizure disorders. Subjects will receive each of these drugs alone and then together. These drugs may be metabolized by similar enzymes in the liver. If an interaction does occur, this study will help to identify the size of the effect.